1. Field of the Invention
This invention relates to a total-internal reflection face pumped laser, and more particularly, to such a laser providing means for fixedly mounting the host within the housing such that the host is substantially isolated from flexing caused by differential thermal expansion of the housing relative to the mounting members.
2. Description of the Prior Art
The face pumped laser, and particularly that of the total internal reflection type, utilizes the major faces of the host for optical pumping thereof and the ends are used for the laser beams. The only surfaces of the host available for mounting are the edges. The prior art has typically provided a host having wedge-shaped edges and mounting was accomplished by chevron-shaped or double-vee wedge rails supported on four sloping feet. The rails also serve to provide the required thermal insulation. Spring-loaded pusher pins serve to clamp the assembly together within the laser head or housing. In operation, differential thermal expansion between the aluminum housing, the glass laser host and the wedge rails cause the rails to rotate about the host, thus producing slab misalignment and flexure of the host itself. The multiple internal reflections within the flexed host result in a deviation angle or optical misalignment of oscillator and amplifier laser beams. This angular deviation results in serious performance degradation.
The prior art has also relied upon springloaded plungers mounted through the housing sidewalls applying forces from the sides of the host to secure the host in place in the laser housing. However, such an arrangement has much the same effect as the mounting arrangement discussed above. Furthermore, both examples of the prior art provide support for the host at only four points. Vibration normal to the plane of the supports results in flexure of the host and a corresponding angular deviation which also causes degraded performance. In addition, the longitudinal restraint typically requires large forces since only the friction between the supports and the host acts to restrain longitudinal motion.
Another form of prior art is shown in U.S. Pat. No. 4,378,601, issued Mar. 29, 1983, to John M. Eggleston, III et al, which consists of a rectangular frame enclosing the ends and sides of the slab. The opening in the frame is for pump radiation and slots are provided in the ends of the frame for the lasing radiation. The members of the frame have a U-shaped cross section to receive the slab. This art generally restrains the slab so that there is no gross movement. For rough usage, such as a laser mounted on a vehicle or aircraft, the U-shaped members of the rectangular frame would have to exactly fit the slab in order to fully restrain the slab. If the fit were not exact under all conditions of temperature, the slab would be fretted, chipped and cracked by rattling around inside the rectangular frame.
Prior art for mounting rods by means of clamps or rings, as shown in U.S. Pat. No. 4,354,272, issued Oct. 12, 1982, to Hans-Peter Schwob et al, rely on the fact that flexure of the rod due to small misalignments of the clamps does not affect the output alignment. For slabs with total internal reflections, flexure of the slab is equivalent to misalignment of the laser resonant cavity. Thus, clamping, without means of eliminating flexure of the host slab, is not adequate for supporting and restraining a slab.
Consequently, a need exists for a mounting structure for the host of a face pumped laser which is capable of isolating the host from flexing caused by differential thermal expansion between the laser housing and the host mounting means.
It is therefore an object of the present invention to provide an improved host mounting structure for a face pumped laser.
It is a further object of the present invention to provide a laser host mounting means for a face pumped laser which is operable to isolate the laser host from flexing caused by differential thermal expansion of the laser housing relative to the host support members.
Other objects and advantages of the present invention will become apparent as the description thereof proceeds.